Carlos Ghosn said the charges are meritless and unsubstantiated. File picture: Charles Platiau / Reuters.

Tokyo - Former Nissan boss Carlos Ghosn said he had been "wrongly accused and unfairly detained" at a high-profile court hearing in Japan on Tuesday, his first appearance since his arrest in November rocked the business world.

Entering the court handcuffed and with a rope around his waist, the once-revered titan of the auto industry mounted a passionate defence against a string of financial misconduct allegations.

The 64-year-old appeared thinner - his family says he has lost up to 20 kilogrammes due to the rice-based diet in his Tokyo detention centre -and was greying at the temples. He appeared in a dark suit without a tie and wore plastic slippers.

"I have been wrongly accused and unfairly detained based on meritless and unsubstantiated accusations," he told the Tokyo District Court, according to a statement prepared in advance and distributed by his representatives.

In a career spanning decades, during which he won praise for turning around the struggling Japanese carmaker, he said he had "always acted with integrity" and had never before been accused of any wrongdoing.

"I have acted honourably, legally and with the knowledge and approval of the appropriate executives inside the company," stressed Ghosn in a clear and steady voice.

He showed no emotion and mostly faced forward or looked down, glancing at the gallery occasionally.

From the moment on November 19 that prosecutors stormed his private jet at a Tokyo airport, the twists and turns of the Ghosn case have gripped Japan and the business world.

At one point, the Franco-Lebanese-Brazilian tycoon appeared on the point of release, only for prosecutors to produce further allegations against him to continue his custody.

In an indication of the interest the case has sparked in Japan, more than 1000 people waited outside the court from the early hours in the hope of getting one of just 14 tickets for the public gallery.

Tuesday's hearing itself caught observers off-guard as Ghosn's lawyers deployed a rarely-used article of the Japanese Constitution to force the court to explain the reasons for his detention.

Presiding Judge Yuichi Tada read out the charges against Ghosn and said he was being detained because he was a flight risk and there was a possibility he would conceal evidence.

The suspect has "bases in foreign countries" and may "escape," Tada said, explaining: "We made a decision that there is need for detention."

Ghosn is expected to be kept in custody until at least January 11.

Reuters